Contributor: Alan Chanter
The gigantic 80-cm kanone known as "Gustav" owed its origin to a 1935 Wehrmacht study into what would be needed to penetrate the thickness of concrete, being boasted of in French newspapers, in the newly completed Maginot Line. Krupp AG, a leading German steelworks and armaments manufacturer, were approached with a request to provide ballistic data for hypothetical guns of 70-cm, 80-cm, and 100-cm calibres. This the factory provided, partly as a propaganda stunt and partly as a design exercise. Here the matter might have rested, except that in March 1936 Hitler paid a visit to the Krupp factory, and raised the same question. The proprietor, Gustav Krupp von Bohlen (1870-1950) was therefore quickly able to provide the Führer with a comprehensive answer based on the earlier calculations. Krupp (no doubt fully aware of the fate that had already befallen Hugo Junker) was keen to assure Hitler that, although the building of such a monster cannon was a difficult proposition, it could in fact be built. After Hitler had departed, Gustav Krupp decided to take a gamble, and set his design team to work on the 80-cm model. In early 1937 he was in a position to lay a set of drawings before Hitler, who approved, and consented to the allocation of 10 million Marks for the project. The only stipulation being, that gun should be ready to demolish the Maginot Line defences by the spring of 1940.

The manufacture of the cannon proved even harder than had been anticipated. Forging and machining the massive barrel posed many difficult problems and the spring of 1940 came and went without the 80-cm gun being completed. Ultimately the Maginot line was simply outflanked by the German Army rather than demolished. Apart from Hitler nobody on the unenthusiastic German General Staff really missed having the wonder weapon.
Towards the end of 1940 the gun barrel was eventually ready and was test fired for the first time on the Hillersleben range near Magdeburg early in 1941. Finally, about a year later, the remainder of the equipment was ready. Taken to the Rugenward range on the Baltic coast of Pomerania, it was assembled and given its final firing tests in the presence of Hitler. Afterwards Krupp presented the Fuhrer with the gun free of charge as his personal contribution to the war effort. The gun was given the name of "Schwere Gustav" in honour of its originator, but the German artillerymen, with a little less respect, soon irreverently began calling it "Dora" (which is why, for a number of years, it was assumed there were two such weapons).

Although termed a railway-gun, the sheer size of Gustav meant that it actually traveled in sections to meet the loading gauge on German railways. Obviously it could not be transported in one piece. The gun itself was broken down into five units; breech ring and block, the barrel in two halves, the barrel jacket, the cradle and the trunnions. The rest of the mounting was split lengthwise so that as well as being dismantled from the top down, it was also broken into two halves for movement. All these components were carried on special flat-wagons, except for the bogie units which ran on their own wheels.
Gustav eventually went to war at the siege of Sevastopol in July 1942. The whole process of assembling Gustav's 1,329 tons took about three weeks and a force of 1,420 men commanded by a Major-General. When fully assembled it would be 141 feet long, 23 feet wide, and the axis of the barrel some 25 foot above the track. A special four-track section had to be laid to put the gun into action; on the inner tracks the gun bogies were assembled and linked together, and on the outer pair ran a gantry crane for assembling the rest of the weapon. Various parts of the mounting were then built up on top of the bogies; the barrel was assembled by inserting the rear half into the jacket and then fitting the front half on and locking everything together with a massive junction nut. The barrel was then fitted into the cradle and the whole assembly hoisted up and lowered onto the mounting. After this the breech ring was fitted to the end of the barrel by another huge nut and the 20-ton breech block slid into place.

Once ready it opened fire on the Soviet fortifications, within the besieged city, with 4.7-ton high-explosive shells effective to a maximum range was 29 miles. With 7-ton concrete-piercing shells a range of 23 miles was achieved, and one such shell is reported to have penetrated 100-foot of earth before detonating inside an underground ammunition store. Some fifty or so of these massive shells were fired into Sevastopol causing immense damage.
After Sevastopol, Gustav trundled out of the lime-light. It was taken off to besieged Leningrad, but the Russians had other ideas and had pushed the German army back before the Gustav could be made ready. Its only other recorded appearance was outside Warsaw in 1944 when some 30 shells were fired into the city during the abortive rising. After that Gustav vanished. Numerous reports of its discovery in pieces, its scrapping, its capture or abandonment have been suggested but none of them stand up to very close examination; spare barrels and ammunition were found, but the gun itself was never seen again (Despite some reports that it was found wrecked on its special train by a US army unit in Bavaria at the end of the war). It seems likely that it was simply scrapped some time during late 1944.

Gustav had cost 10 million Marks, and the price of the ammunition is unknown, but its only achievement seems to have been the demolition of a few Soviet and Polish defences and one ammunition dump, which was hardly a great achievement for a weapon that had cost so much in effort and money. For propaganda, or for boosting morale, or for frightening an unsophisticated enemy, Gustav, and the other super-guns, may have had their uses, but as a cost effective weapon of war it was nevertheless a non-starter.
The heaviest gun ever built was ordered by Hitler. He wanted the gun to be able to pierce a meter of steel, seven meters of concrete, or thirty meters of dense earth. The original target was the French Maginot Line, the fortifications which were nearly impervious to anything the Nazis had before the war.

Krupp responded by designing a 800 mm railway gun, mounted, due to its great weight, on double tracks. Its great weight also meant that it could only be turned by pushing it on curved railroad tracks. Preparing a firing position and assembling the gun, which was always transported in parts, took six weeks.

The gun fired two types of ammunition: a high-explosive shell containing a 700-kilogram explosive charge and an armor-tipped concrete-piercing projectile containing a 250-kilogram charge and capable of penetrating over 250 feet of reinforced concrete before exploding.

Due to the Krupp tradition of naming heavy cannon after family members (see Big Bertha), the first 800 mm gun was named Gustav after the head of the family, Gustav Krupp von Bohlen und Halbach, who initiated the project.

It is unclear whether Krupp ever manufactured a second gun of this caliber. It may be that the gun known as Dora was actually the original Gustav after being refitted. Dora was named after the chief engineer's wife. I will continue to refer to the 800 mm gun(s) used in the war as Dora, like most sources.

The original order was for three guns, but it is fairly certain that a third one was never finished.

The Maginot Line was bypassed and France had fallen in 1940 before any of these guns were finished, so new targets were sought. High Command's plans to use them against the British fortress of Gibraltar were scrapped after General Franco refused to allow firing the gun from Spanish soil.

While the gun was being demonstrated to Hitler and the Oberkommando des Heeres, Dr. Müller of Krupp told the Führer that it could be used against enemy armor. Panzer General Guderian was stunned by this statement, and replied to Hitler that, while the gun could indeed be fired at tanks, it would never be able to hit them.

Among the special equipment developed by Krupp to operate the gun was an entirely new railway engine, the diesel-electric D 311. It was designed to move Dora in pairs on the curved track to aim the gun, and because of this it had to be able to pull a vast load at very slow speeds.

In June 1942, Dora was used in battle for the first time, firing at the heavily fortified Crimean port of Sevastopol. Spotter aircraft noted the impressive performance of the gun. Fire from Dora and other heavy artillery destroyed Forts Stalin, Lenin, Molotov and Maxim Gorki. A single round from the Dora destroyed an ammunition dump, built under the Severnaya Bay and considered invulnerable to artillery by the Soviets, and a near miss capsized a large ship in the harbor. The barrel was worn out during the siege and replaced. It may have fired a total of 300 rounds during testing and near Sevastopol.
Dora was set up near both Stalingrad and Leningrad in late 1942, but in both cases it was hurriedly withdrawn to avoid capture (it would have been very bad publicity to have the Soviets capture the gun and use it against the Germans, even though it was of relatively little military significance).

Dora appeared again outside Warsaw during the September 1944 uprising, firing 30 rounds into the Warsaw Ghetto. After this, it was never used again. The blown-up remnants of a gun of this type were discovered in Bavaria by the Allies.
The 800 mm shells could destroy pretty much anything they hit. However, the gun was ludicrously expensive to build and maintain. First of all, it took a massive amount of steel to build, and the barrel wasn't good for more than a few hundred rounds. Also, the gun required more than a thousand troops to move, assemble, maintain and reload. And since it was such a huge target and could hardly be kept in secret when in use, it needed heavy air defense and could be destroyed by a single successful bombing raid. These factors made it an impractical weapon in war, especially since it was really only suited for destroying massive fortifications (although it could take out a city block with a single shot, normal heavy artillery could do this just as well, and cheaper), and there simply weren't any within range after France and Sevastopol were taken.

Dora was yet another example of the Nazis' obsession with equipment that was either much too heavy or much too advanced to be deployed in any practical manner.
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